Watson f



(R8 Model.)

W. F. QUINBY. Y Forming Passages or Ducts in Plastic Ma, teria.l.-

No. 240,459. Patented April 19,1881.

UNITED STATES PATENT OFFICE.

WATSON F. QUINBY OF WILMINGTON, DELAWARE.

FORMING PASSAGES OR DUCTS IN PLASTIC MATERIAL.

SPECIFICATION forming part of Letters Patent No. 240,459, dated April 19, 1881.

Application filed February 25, 1881. (No model.)

To all whom it may concern Be it known that I, WATSON F. QUINBY, a citizen of the United States, residing in VVilmington, Delaware, have invented an Improvement in Forming Passages or Ducts in Plastic Material, of which the following is a specification.

My invention relates to the formation of passages or ducts in a material or composition which is, in the first instance, in a fluid, semifluid, or plastic condition, but which becomes hard, or comparatively hard, in drying or coolingas, for instance, plaster-of-paris, or R0- man or hydraulic cement mixed with more or less water, or common plaster or clay, or composition of which any of the above ingredients form a part, or composition of an asphaltic character rendered plastic by heat; and my invention consists in first embedding an elastic core 'in the material while it is in a condition to be formed round the said core, and, after the material is wholly or partly dry or cool, and comparatively hard, withdrawing the core, which is contracted by the tensile strain applied to it during withdrawal, and thus easily leaves the mass in which it was embedded.

My invention is based on a discovery which may be best explained by reference to Figure l of the accompanying drawings, in which- Arepresents an elastic core, preferably a solid strip or tube of rubber, and B a block of plaster-of-paris, in which the core was embedded while the plaster was in a fluid or semifluid condition.

I have found that after the plaster has become 'set by partial drying the core can be withdrawn by pulling it at one end while the plaster blockis held, the withdrawal of the core by a comparatively slight effort being due to its lateral contraction while under tensile strain. The increasing of the length of the block does not demand a materially-increased effort to withdraw the core, the passage formed through the. block by the said core being clean and smooth.

Passages or ducts can be thus formed in I masses of hydraulic or Roman cement, in clay or common plaster, in asphaltic compounds, or indeed in any material or composition which is plastic enough to permit the embedding of the core in it, and which will become hard, or comparatively hard, when dried or cooled; but it is not necessary that the material should be perfectly dry and hard before the core is withdrawn. ,It may be comparatively soft, if the material possesses sufficient coherence to prevent disintegration or collapsingduring the withdrawal of the core.

An application of my invention to the formation of underground passages or ducts is illustrated in Figs. 2 and 3, in which D represents a trench dug in the ground, and A the elastic core embedded in a mass, B, of plastic material deposited in the trench. After the material has become sufficiently hard, the elastic core is pulled so far from it that a small portion only of the said core remains in the mass, the remaining or greater portion of the core being now surrounded with other plastic material, which is a continuation of that first deposited in the trench, and when this second supply of material is dry enough the core is again pulled outward, and this operation may be continued to any length desired.

The application of my invention to the laying of underground-telegraph wires is shown in Fig. 4, the insulated Wires or cable H oeing placed withing a tubular elastic core, the latter being surrounded with plastic material, as in the case referred to above, and the tube being withdrawn while the cable is held, the cable thus remaining in the passage or duct formed by the core.

The invention is applicable to many other purposes. The elastic core, for instance, may be used for the formation of passages in loam molds, for castings, or even in sand molds, where coherence is imparted to the sand by a- 0 slight moisture. It may also be used in the manufacture of clay pipes, hollow bricks, &c.

It is not essential that the core should be cylindrical, as it may be of any shape or size suggested by the desired form or size of the 5 passage.

I claim as my invention- The mode herein described of forming passages or ducts in material or composition which may be fluid, semi-fluid, or plastic, but I which becomes hard in drying or cooling, the In testimony WhereofI have signed my name said mode consisting in first embedding an to this specificationin the presence of two sub-' elastic core in the said material, and when the scribing Witnesses.

latter is dry or cool, or partially so, cali'sing WATSON F. QUINBY. the lateral contraction of the core by tensile strain and Withdrawing the said core, all substantially as set forth.

Witnesses:

JAMES F. ToBIN, HARRY SMITH. 

